Wind energy, because of its variable nature, is not suited to be the lone or primary source of a grid’s total electricity, according to a new Reason Foundation study. If it is used to produce more than 10-to-20 percent of a system’s electricity, wind power increases operating costs due to the need for expensive storage facilities or continuously available CO2-emitting backup power generation facilities.

The new Reason Foundation report uses a full year’s worth of hour-by-hour power grid data from PJM Interconnection, which manages the electrical grid in part of the Eastern United States, to simulate how wind would’ve supplied the necessary power to customers in 2009. Reason’s models show wind power would’ve failed to supply all of the electricity PJM customers needed over 50 percent of the time.

Thus, if wind is going to produce a large percentage of a grid’s electricity it will be necessary to build expensive energy storage facilities or reserve power generation facilities to supply power when there is not enough wind to meet energy demands at any given time and to prevent brownouts and blackouts.

The study shows that as more reserve power is needed, the environmental benefits of wind power decrease due to the C02 emissions from those facilities, which rely upon fossil fuels and must operate even when not being used, in order to ensure reliability of the electrical grid.

The study concludes that, given the costs involved, the practical upper limit for wind power’s contribution to an electricity grid is 10 percent of the total energy, which would produce a 9 percent reduction in CO2 emissions.

“Very high wind penetrations are not achievable,” said William Korchinski, author of the Reason Foundation study. “As wind’s share increases, system reliability will be adversely affected disproportionately-unless adequate reserve power is available. That power reserve is expensive and lowers any possible environmental benefits.”